Control system for surface water heating for irrigation and frost prevention

ABSTRACT

A control system for a surface water heating system for irrigation is described. The control system comprises a controller, memory operatively coupled to the controller, a first threshold value stored in memory, a sensor operatively coupled to the controller, a geothermal heated water source, a heat exchanger, and a valve configured to regulate a flow of water between the geothermal hated water source and the heat exchanger. The controller performs a periodic comparison between the sensor input and the first threshold value. If the sensor input value falls below the first threshold value, the controller generates an instruction to open the valve. Some embodiments also comprise a second threshold value. If, after the valve has been opened, the sensor input rises above the second threshold value, the controller generates an instruction to close the valve.

CROSS REFERENCES TO RELATED APPLICATIONS

This patent application is related to co-pending patent application13/081,984 filed on Apr. 7, 2011 and co-pending patent application13/082,017 filed on Apr. 7, 2011, and

this patent application claims the benefit of provisional patentapplication 61/322,739 filed on Apr. 9, 2010 and

claims the benefit of provisional patent application 61/322,761 filed onApr. 9, 2010 and

claims the benefit of provisional patent application 61/322,773 filed onApr. 9, 2010,

which are hereby incorporated by reference in their entirety.

FIELD

The present invention relates to the control system for a surface waterheating. More particularly, the invention is related to a control systemfor engaging and disengaging the surface water heating system inresponse to at least one weather condition for irrigation and frostprevention.

BACKGROUND

Surface water resources are generally more suitable for irrigation thangroundwater resources because of the water quality associated withsurface waters. Additionally, hot springs associated with geothermalsources may include dissolved gases and heavy metals. Therefore, heatedwater from geothermal sources may contain undesirable contaminants whichmake the water unsuitable for agricultural irrigation.

Surface water resources are subject to daily, monthly, seasonal andannual changes in temperature. These changes in temperature may resultin cold temperature spikes, which may in turn lead to frozen pipes andfrozen valves. Additionally, during cold temperature many plants may bedamaged or killed by freezing temperatures or frost.

Frost is the solid deposition of water vapor from saturated air; frostis formed when solid surface are cooled to below the dew point of theadjacent air. There are many types of frost. Many plants can be damagedor killed by freezing temperatures or frost; and the damage depends onthe type of plant and tissue exposed to the low temperatures.

Vines for winemaking also can be affected by cold temperature spikes.For example, frost injury may occur to grapevine tissue and buds.Irrigation with sufficiently warm water during a freeze may provideprotection to the plants.

The selective inverted sink is a device used by farmers to protectplants from frost by blowing the denser cold air from ground leveltowards the sky, thereby circulating the warmer air down to the groundlevel. However, the energy requirements for the selective inverted sinkare substantial and this additional expense generally results in alarger carbon footprint.

Thus, it would be desirable to have an affordable system for preventingthe damage to plants exposed to low temperatures and frost.

Furthermore, it would be desirable to provide a control system for thesurface water heating system for irrigation and frost prevention.

SUMMARY

A control system for a surface water heating system for irrigation andfrost prevention is described. The control system comprises acontroller, memory operatively coupled to the controller, a firstthreshold value stored in memory, a sensor operatively coupled to thecontroller, a geothermal heated water source, a heat exchanger, and avalve configured to regulate a flow of water between the geothermalhated water source and the heat exchanger. The controller performs aperiodic comparison between the sensor input and the first thresholdvalue. If the sensor input value falls below the first threshold value,the controller generates an instruction to open the valve, allowing thegeothermal heated water to flow through the heat exchanger. In thismanner, surface water may be heated by geothermal heated water in a heatexchanger. Some embodiments also comprise a second threshold value. If,after the valve has been opened, the sensor input rises above the secondthreshold value, the controller generates an instruction to close thevalve.

In some embodiments, the control system comprises a controller, memoryoperatively coupled to the controller, a first threshold value stored inmemory, an air temperature sensor operatively coupled to the controller,a buffer in memory configured to store data generated by the sensor, ageothermal heated water source, a heat exchanger, and a valve configuredto regulate a flow of water between the geothermal hated water sourceand the heat exchanger. The controller performs a periodic comparisonbetween the sensor input and the first threshold value. If the airtemperature as measured by the air temperature sensor falls below thefirst threshold value, the controller evaluates the contents of thebuffer to determine whether the air temperature has been decreasing. Ifthe air temperature has been decreasing, the controller generates aninstruction to open the valve. Some embodiments also comprise a secondthreshold value. If, after the valve has been opened, the airtemperature rises above the second threshold value, the controllerevaluates the contents of the buffer to determine whether the airtemperature has been rising. If the air temperature has been rising, thecontroller generates an instruction to close the valve.

In another embodiment, the control system comprises a sensor, ageothermal heated water source, a heat exchanger, a means for regulatinga flow of water between the geothermal heated water source and the heatexchanger, and a means for comparing the sensor input to a firstthreshold value. If the sensor input value falls below the firstthreshold value, water is conducted from the geothermal heated watersource to the heat exchanger. Some embodiments also comprise a means forcomparing the sensor input to a second threshold value. If, after theflow of water from the geothermal heated water source to the heatexchanger has been initiated, the sensor input value rises above thesecond threshold value, the flow of water between the geothermal heatedwater source and the heat exchanger is stopped.

In some embodiments, the control system comprises an air temperaturesensor, a geothermal heated water source, a heat exchanger, a means forregulating a flow of water between the geothermal heated water sourceand the heat exchanger, a means for comparing the sensor input to afirst threshold value, and a means for determining whether the airtemperature as measured by the air temperature sensor has beendecreasing. If the air temperature falls below the first threshold valueand the air temperature has been decreasing, water is conducted from thegeothermal heated water source to the heat exchanger. Some embodimentsalso comprise a means for comparing the sensor input to a secondthreshold value and a means for determining whether the air temperatureas measured by the air temperature sensor has been increasing. If, afterwater has been conducted from the geothermal heated water source to theheat exchanger, the air temperature rises above the second thresholdvalue and the air temperature has been increasing, the flow of waterbetween the geothermal heated water source and the heat exchanger isstopped.

A method for controlling an irrigation water system is also described. Acontroller performs a periodic comparison between a sensor input valueand a first threshold value stored in memory. If the sensor input valuefalls below the first threshold value, the controller generates aninstruction to open a valve between a geothermal heated water source anda heat exchanger. In some embodiments, if the valve is open, thecontroller performs a periodic comparison between a sensor input valueand a second threshold value. If the sensor input rises above the secondthreshold value, the controller generates an instruction to close thevalve.

In another embodiment, the method comprises using a controller toperform periodic comparison between an air temperature sensor and afirst threshold value stored in memory. If the air temperature asmeasured by the air temperature sensor falls below the first thresholdvalue, the controller determines whether the air temperature has beendecreasing. If the air temperature has been decreasing, the controllergenerates an instruction to open a valve between a geothermal heatedwater source and a heat exchanger. In some embodiments, if the valve isopen, the controller performs a periodic comparison between the airtemperature as measured by the air temperature sensor and a secondthreshold value. If the air temperature rises above the second thresholdvalue, the controller determines whether the temperature has beenincreasing. If the air temperature has been increasing, the controllergenerates an instruction to close the valve.

FIGURES

The illustrative embodiment will be more fully understood by referenceto the following drawings which are for illustrative, not limiting,purposes.

FIG. 1 shows an illustrative graph indicating the low temperature spikesthat may occur during the growing season.

FIG. 2 shows an illustrative irrigation water heating system.

FIG. 3 shows an illustrative heat exchanger for an irrigation waterheating system.

FIG. 4 shows illustrative valves for an irrigation water heating system.

FIG. 5 a shows an illustrative control system for the irrigation waterheating system of FIG. 4.

FIG. 5 b shows an illustrative graph indicating points at which theirrigation water heating system may be engaged and disengaged relativeto air temperature.

FIG. 5 c shows an illustrative flow chart for the operation of thecontrol system.

FIG. 6 shows an illustrative system for using of conduit insulation inan irrigation water heating system.

FIG. 7 shows an illustrative system for generating power using excessheat from the irrigation water heating system.

FIG. 8 a shows a side elevation of an illustrative agricultural trellis.

FIG. 8 b shows a front elevation of an illustrative agriculturaltrellis.

FIG. 9 a shows an illustrative trellis with integrated mounted drip andspray irrigation systems and protective net.

FIG. 9 b shows an illustrative trellis with its protective net deployed.

FIG. 10 a shows an illustrative first spray pattern of a nozzle in aspray irrigation system.

FIG. 10 b shows an illustrative second spray pattern of a nozzle in aspray irrigation system.

FIG. 11 shows an illustrative flow chart for the operation of the dripand spray irrigation systems.

FIG. 12 a shows an illustrative diagram for explaining the transitionsbetween system states in the drip irrigation system.

FIG. 12 b shows an illustrative diagram for explaining the transitionsbetween system states in the spray irrigation system.

DETAILED DESCRIPTION

Persons of ordinary skill in the art will realize that the followingdescription is illustrative and not in any way limiting. Otherembodiments of the claimed subject matter will readily suggestthemselves to such skilled persons having the benefit of thisdisclosure. It shall be appreciated by those of ordinary skill in theart that the surface water heating system, control systems, and methodsdescribed hereinafter may vary as to configuration and as to details.

In the embodiments described herein, the illustrative geothermal heatedfluid is water. Other illustrative geothermal heated fluids include, butare not limited to water, salt water, brine solutions, steam, mud, andsimilar fluids (including gases) that are heated by geothermal energy.

In general, the geothermal heated fluid is used in a heat exchangesystem so that the geothermal heated fluid does not come into contactwith the surface water. In this manner, damage to irrigation systemsfrom frozen surface water in pipes can be avoided. Moreover, the heatedirrigation water can be used to prevent frost damage to irrigated cropssuch as grapevines.

In the embodiment described herein the term geothermal heated fluid andheated water are used interchangeably. In certain embodiments, thegeothermal heated fluid is associated with a liquid phase, a gas phase,and the combination thereof. For example, a hot spring can include a gasphase such as steam, and the liquid phase may be a brine, water or mud.

Referring now to FIG. 1, an illustrative graph 100 shows exemplaryoutside air temperatures during a growing season in a region where theirrigation water heating system may be used. For example, the growingseason for a vineyard at a high elevation, such as 5000 feet, may occurbetween April and November as indicated in FIG. 1. Exemplary high andlow temperatures are indicated by curves 102 and 104, respectively.During the growing season, the low temperature regularly drops below atemperature at which frost on agricultural plants becomes a concern,e.g. 35° F., as indicated at 106-112. The low temperature spikes maypresent a danger to agricultural plants, such as grapevines, becausefrost injury may occur to the plants. Irrigation can provide a degree ofprotection from frost, and the benefit of irrigation during a freezeincreases as the temperature of the irrigation water rises.

Referring to FIG. 2, an illustrative irrigation water heating system 200is shown. Geothermal water source 202 includes, for example, a well, hotspring, and other such sources containing geothermal heated fluid. Forexample, geothermal water is pumped out of the geothermal water source202 through conduit 204 by geothermal water pump 206. The temperature ofthe geothermal water is high relative to the temperature of the surfacewater, for example, 195° F. The geothermal water is then pumped by pump210 into a heat exchanger 212.

A geothermal water conduit system comprised of conduit segments 204,206, and 208 is a channel along which water flows. It may be, forexample, pipe or tubing. The conduit may comprise different materials atdifferent segments. For example, conduit segment 204 may be a pipe ofsteel while conduit segment 208 may be an open channel in the ground.

Because the conduit segments 204, 206 and 208 and heat exchanger 212form a loop originating at and returning to geothermal water source 202,the geothermal water conduit system is also referred to as thegeothermal loop. The pump, 210, displaces geothermal water along thegeothermal water loop.

Heat exchanger 212 is a device that transfers heat from the geothermalheated water stream to the surface water resources, without allowing thegeothermal heated water to come into contact with the surface water. Inone illustrative embodiment, the heat exchanger may have, for example, ashell and tube design. In a shell and tube heat exchanger, one fluidflows through a shell while the other fluid flows through tubes locatedwithin the shell. In a shell and tube heat exchanger, the heat exchangerhas a shellside inlet, where the hot water stream enters the heatexchanger shell; a shellside outlet, where the hot water stream exitsthe heat exchanger shell; a tubeside inlet, where the cold water streamenters the heat exchanger tubes, and a tubeside outlet, where waterexits the heat exchanger tubes. An illustrative shell and tube heatexchanger is explained further in the description of FIG. 3, below.

Alternatively, the heat exchanger 212 may have, for example, aplate-frame or plate-coil design. Also, in certain embodiments a seriesof heat exchangers is used to provide the desired amount of heating forthe surface water.

In the illustrative embodiment shown in FIG. 2, the geothermal heatedwater enters the heat exchanger 206 through the shellside inlet 214 andexits the heat exchanger through the shellside outlet 216. Thegeothermal heated water is returned along conduit 208 to the geothermalwater source 202. The geothermal heated water in the return path hasbeen cooled in the heat exchanger, for example, to 70° F.

Surface water is pumped by surface water pump 222 from surface watersource 220 into the heat exchanger 212 via conduit segments 224 and 226.The surface water enters the heat exchanger 212 through the tubesideinlet 218 and exits the heat exchanger through the tubeside outlet 220.The irrigation water heating system may be engaged, for example, whenthe surface water has a temperature of 35° F. The heated surface wateris delivered to the irrigation manifold 230 via the conduit segment 228.The heated surface water has been heated within the heat exchanger to atemperature beneficial to preventing frost formation on agriculturalplants, for example, 50° F. At the irrigation manifold 230, the surfacewater stream is divided into multiple streams to provide irrigationcoverage at intervals along the crop area.

The irrigation manifold 230 comprises multiple irrigation channels orrows, each of which may be controlled by a valve such as valve 232. Thevalve regulates the flow of water through the channel. The valvetypically has two states, an open state and a closed state. When thevalve is in the open state, water can flow through the valve. When thevalve is in the closed state, water is prevented from flowing throughthe valve.

Each irrigation channel provides irrigation water to a different segmentof an agricultural field. The valves are opened and closed such thatirrigation water flows to each row serially. Thus, a first valve 232 isopened, and water flows through a first irrigation channel 234. When thedesired amount of water has been delivered to the segment served byirrigation channel 234, the first valve 232 is closed, and a secondvalve 236 is opened to provide irrigation water through a secondirrigation channel 238.

In some embodiments, the irrigation manifold comprises a second set ofirrigation channels (not shown) for a spray irrigation system, whichprovides heated irrigation water as mist or spray. The irrigationchannels of the spray irrigation system have valves to control deliveryof irrigation water to the irrigation channels. The irrigation channelsof the spray irrigation system terminate in an outlet such as asprinkler nozzle (not shown) or mister nozzle (not shown) that dispersesthe heated irrigation water as mist or spray. The sprinklers or mistersmay be at ground level or elevated above ground level by a stand,trellis, or other such device that elevates the mister or sprinkler.

When irrigation with heated water is used to prevent the formation offrost on plants, the plants may receive more water than would typicallybe applied for irrigation. The excess water may be harmful to theplants. The irrigated area may feature a drainage system (not shown) toavoid harm to the plants from excess irrigation.

Referring to FIG. 3, an illustrative shell and tube heat exchanger 300is shown. A first fluid flows enters the shell at shellside inlet 302and exits the shell at shellside outlet 304. A second fluid enters tubeinlet plenum 310 at tubeside inlet 308. Tubes 312 and tube 314 branchoff of tube plenum 310. The second fluid flows through tubes 312 and 314in the direction indicated by the arrows. The second fluid flows fromthe tubes into tube outlet plenum 316 and exits the heat exchanger attubeside outlet 306. The first and second fluids are shown in acounterflow arrangement with the first fluid flowing in the oppositedirection of the second fluid, however, other the heat exchanger may bedesigned with alternative flow configurations, such as a parallel flowconfiguration.

In the illustrative embodiment, the first geothermal heated fluid may begeothermal water or geothermal gas. The second fluid is a surface water.The illustrative surface water may be drawn from a lake, stream,irrigation ditch, or other such surface water source. As theillustrative geothermal heated water and the surface water flow throughthe heat exchanger, heat from the geothermal water is transferred to thesurface water. The heat exchanger is shown with two tubes forillustrative purposes, however, the number of tubes in the heatexchanger will vary depending on the amount of heat transfer requiredand respective rates of flow of the first and second fluids.

The heat exchanger may include baffles such as baffle 318 which create atortuous path for fluid flowing through the shell. The first fluid flowsunder baffle 318 and then over baffle 320, as indicated by the curvedarrows. The tortuous route increases the amount of contact between thefirst fluid and the second fluid which increases the amount of heatexchanged between the fluids. It will be appreciated that various baffleconfigurations, as well as other methods for creating a tortuous routethrough the heat exchanger, may be used.

Referring to FIGS. 4 and 5 there are shown illustrative valvesassociated with the irrigation system 400, in which the valves arecontrolled by illustrative control system 500. There are three valves414, 409 and 408 displayed in FIGS. 4 and 5. The first valve 414controls the flow of geothermal water from the illustrative heatedgeothermal water source 424 to the heat exchanger 422. The second valve409 controls the flow of the surface water to the heat exchanger 422, inwhich the heated surface water is transferred along conduit 419 anddelivered to the irrigation manifold 410. The third valve 408 is abypass valve that is opened when surface water heating is not utilized,so the surface water flows directly from the surface water source 402along conduit 404 to irrigation manifold 410. One or more sensors, asshown in FIG. 5 and described in further detail below, trigger theopening and closing of the valves and pumps associated with theirrigation apparatus, systems and methods described herein.

In one embodiment, an illustrative air temperature sensor 504 is aninput to the control unit 500. The air temperature data generated by theair temperature sensor 504 may be collected in a buffer in the controlunit memory.

For example, if the air temperature drops below a first thresholdtemperature, e.g. 34° F., the controller generates an instruction toopen valve 414, open valve 409 and close valve 408 and engage the waterheating system. Referring to FIG. 5 b the air temperature of 34° F.occurs at intersection 518, and at approximately midnight the surfacewater heating system is triggered.

In some embodiments, when the air temperature drops below the firstthreshold temperature, the control unit determines from the airtemperature data in the buffer whether the temperature has been fallingover a predetermined period of time. If the air temperature has droppedbelow a first threshold temperature and the temperature has beenfalling, the controller generates an instruction to engage the waterheating system.

In another embodiment, the controller will also determine a rate ofchange in temperature, which is compared against a threshold rate storedin memory. The rate of change in temperature may be an additional factorused by the controller in the determination of whether the controllerwill generate an instruction to engage the water heating system.

When the irrigation water heating system is engaged, the followingillustrative events take place: the control unit 500 will close valve408 to shut off the flow of surface water along conduit 404; valve 409is opened and the water flowing along conduit 404 is rerouted to theheat exchanger 422 via conduit 412; and the control unit will open valve414 to allow geothermal water to flow from geothermal water source 424into the heat exchanger 422 via conduit 416. Additionally, geothermalpump 426 may be engaged.

If the air temperature as measured by the air temperature sensor risesabove a second threshold temperature, for example 35° F., the controlsystem 500 generates an instruction to disengage the water heatingsystem.

In some embodiments, when the air temperature rises above the secondthreshold temperature, e.g. 35° F., the controller determines from airtemperature data stored in the buffer whether the air temperature hasbeen rising over a predetermined period of time. If the air temperatureis above the second threshold temperature and the controller determinesthat the temperature has been rising, the controller will generate aninstruction to disengage the irrigation water heating system.

When the water heating system is disengaged, geothermal water valve 414is closed to stop the flow of geothermal water. Additionally, geothermalpump 426 may be disengaged. Heated surface water valve 409 is closed andsurface water bypass valve 408 is opened to enable the surface water toflow directly into the irrigation manifold without passing through theheat exchanger.

Referring to now to FIG. 5 a, the illustrative control system 500comprises controller 502. An illustrative controller includes aprocessor, irrigation controller, PID controller and other such devicesthat monitor and affect the operation conditions of a given dynamicsystem. A memory 503 is shown. The memory includes, by way of exampleand not limitation, RAM, ROM, EPROM, EEPROM, flash memory, L1 Cache, L2Cache and other such memory associated with controller 502. Thecontroller receives input from sensor S1 shown at 504. S1 may be, forexample, an air temperature sensor. The controller may receive inputfrom additional sensors S2, shown at 506, through Sn.

Controller 502 generates instructions to control the flow of waterthrough the water heating system. The controller may generate aninstruction to control the flow of the heated geothermal water 508,typically by generating an instruction to open a valve between thegeothermal water source 424 and heat exchanger 422. The controller maygenerate an instruction to close valve 406 to divert surface water 510through the heat exchanger so that heated irrigation water is providedto irrigation manifold 410.

The controller also controls the flow of water within the irrigationmanifold 410, which comprises irrigation conduits to provide water todrip irrigation systems to each row in an agricultural field, with theflow of water to the irrigation conduits controlled by valves V₁-Dripthrough V_(n)-Drip, as shown at 512-516. The irrigation water may beprovided to one irrigation conduit at a time. To provide irrigationwater to the irrigation conduits serially, the controller 502 maygenerate an instruction to open valve V₁-Drip. When the desired amountof water has been provided via V₁-Drip, the controller generates aninstruction to close the valve V₁-Drip. Subsequently, the controllergenerates an instruction to open a valve V₂-Drip. When the desiredamount of water has been provided via V₂-Drip, the controller generatesan instruction to close the valve V₂-Drip. The controller continues togenerate instructions to open and close valves to the irrigationconduits until the row served by V_(n)-Drip has received the desiredamount of water. In one embodiment, the controller uses a value storedin memory to determine the amount of water required for each irrigationconduit. The controller 502 may generate instructions to control valves508-510 and 512-516 such that the drip irrigation system provides heatedirrigation water, unheated irrigation water, or no irrigation water.

Irrigation manifold 410 may also provide water to spray irrigationoutlets via valves V₁-Spray through V_(n)-Spray, as shown at 522-526,which control the flow of water to irrigation conduits serving the rowsof an agricultural field. The irrigation conduits of the spray systemterminate in nozzles which deliver irrigation as a mist or a spray Thespray system valves may be activated serially, as described above withrespect to the drip system valves. The controller 502 may generateinstructions to control valves 508-510 and 522-526 such that the sprayirrigation system provides heated irrigation water or no irrigationwater. The spray irrigation system may provide heated irrigation waterindependently of, or alternatively, at the same time as the dripirrigation system provides irrigation water to a row in an agriculturalfield. In one embodiment (not shown), the spray system and the dripsystem are activated by the same set of valves.

In operation, the first and second threshold temperatures that affectthe control system 500 shall vary based on the agricultural plantsrequiring protection from frost, soil type, soil moisture, airtemperature and other weather conditions.

The frost point temperature is a temperature at which water vaporcondenses from the air and deposited as frost. Frost may be damaging toplants as discussed above. Frost point is related to the humidity of theair, which is a measure of the amount of water vapor in the air. Asensor for detecting the humidity of the air may be used as an input tothe control system. The sensor may be, for example, a capacitiverelative humidity sensor.

In some embodiments, the controller may use an alternative sensor inplace of the air temperature sensor to determine when the irrigationwater heating system is to be engaged and disengaged. For example, thecontroller may make a determination based on the temperature as measuredby a soil temperature sensor. Alternatively, the controller may use morethan one sensor input in its determination of when to engage theirrigation water heating system. The controller may use input from atleast one of an air temperature sensor, a humidity sensor, a barometricpressure sensor, a soil temperature sensor, a soil moisture sensor and awind velocity sensor to make the determination. It will be recognizedthat additional sensor types may be used as an input that the controllerwill use in a determination of when to engage and disengage theirrigation water heating system.

The temperature sensor measures the temperature of its surroundings andoutputs a signal corresponding to the measured temperature. Themeasurement may be taken with, for example, a thermistor. The controlsystem uses at least one temperature signal to determine when to engageand disengage the irrigation water heating system.

Moist soil is comparatively more able to retain heat and provideprotection to plants against cold weather than a drier soil.Accordingly, a sensor for detecting the moisture of the soil may be usedas an input to the control system. The soil moisture sensor determinesthe amount of moisture in the soil, for example, by measuring thevolumetric water content of the soil, and outputs a signal correspondingto the measured moisture level. The soil moisture sensor may use, forexample, a frequency domain reflectography approach in which radiofrequency waves are used to determine the dielectric properties of thesoil.

In some embodiments, the control system comprises a user interface. Theuser interface allows the user to make changes to the functionality ofthe control system. For example, the user interface may allow the userof the irrigation water heating system to alter a threshold temperaturestored in memory. In another example, the user interface allows the userto change the instructions generated by the controller in response tothe input information it receives. The user interface may also allow theuser to add and subtract inputs to the control system.

The user interface may be located on a remote terminal, whichcommunicates with the controller over a network. Alternatively, the userinterface may comprise a keypad operatively coupled to the controllerand a display operatively coupled to the controller.

Referring to FIG. 5 b, an illustrative graph indicating points at whichthe irrigation water heating system may be engaged and disengagedrelative to air temperature is shown. FIG. 5 b shows an exemplaryillustration of the changes in air temperature over the course of a dayin an area where agricultural frost damage is of concern. The irrigationwater heating system may be engaged when the air temperature drops below34° F. at approximately midnight, as shown at intersection 518.Controller 502 may also examine air temperature data stored in a bufferin memory to determine whether the air temperature has been falling. Ifthe air temperature has been falling over a predetermined period of timeand the air temperature is below 34° F., the controller generates aninstruction to engage the irrigation water heating system.

The irrigation water heating system may be disengaged when the airtemperature rises above 35° F. at about approximately 7:30 AM, as shownat intersection 520. The air temperature data stored in a buffer inmemory may also be used by the controller to determine whether thetemperature has been rising. If the air temperature has been rising overa predetermined period of time and the air temperature is above 35° F.,the controller generates an instruction to disengage the irrigationwater heating system.

Referring to FIG. 5 c, a method 550 for engaging and disengaging thewater heating system is shown. The method begins at decision diamond554, in which the control system compares the air temperature asmeasured by an air temperature sensor against a first thresholdtemperature. If the air temperature is lower than the first thresholdtemperature, the method proceeds to decision diamond 556, in which thecontrol system determines whether the air temperature has been decliningover a predetermined period of time. For example, the control system maydetermine that the air temperature has been declining if the temperaturestored at time t in the buffer is lower than the temperature stored attime t-1, and the temperature stored at time t-1 is lower than thetemperature stored at a time t-2, and so on through time t-n where n isthe number of temperature readings stored in the buffer. Alternatively,n may be a subset of the temperature readings stored in the buffercorresponding to a predetermined time period.

If the air temperature has been declining, the method proceeds to block560. In block 560, the valve 414 in the conduit 416 connecting thegeothermal water source to the heat exchanger 422 is opened. The methodproceeds to decision diamond 562, in which the control system comparesthe air temperature against a second threshold temperature. If the airtemperature is greater than the second threshold temperature, the methodproceeds to decision diamond 564 where the control system determineswhether the air temperature has been rising over a predetermined periodof time. For example, the control system may determine that the airtemperature has been rising if the temperature stored at time t in thebuffer is higher than the temperature stored at time t-1, and thetemperature stored at time t-1 is higher than the temperature stored ata time t-2, and so on through time t-n. If the air temperature has beenrising, the method proceeds to block 566. In block 566, valve 414 isclosed to stop the flow of geothermal water through the heat exchanger.

Referring to FIG. 6, an illustrative system 600 for using conduitinsulation in an irrigation water heating system is shown. It may bebeneficial to insulate the water traveling between the geothermal watersource 602 and the heat exchanger 604 to minimize loss of heat from thegeothermal water along the conduit 606. Conduit 608 may be insulated tominimize the loss of heat from surface water heated in the heatexchanger 604 as the surface water is delivered to irrigation manifold610. The locations for conduit insulation in the irrigation waterheating system are indicated by dotted lines along conduits 606 and 608.The insulated conduits may be prefabricated pipes containing insulatingmaterial such as fiberglass, or may be fabricated from a pipe surroundedby an insulating material such as a polymer foam. Insulated conduits mayalso be pipes which are buried and insulated by the ground.

Referring to FIG. 7, an illustrative system 700 for generating powerusing excess heat from a geothermal heated fluid is shown. Thegeothermal heated fluid 702 may produce more heat than is necessary forheating surface water in heat exchanger 704. Excess heat may be producedperiodically or it may always be available. Geothermal heat may be usedto generate power whenever the irrigation water heating system isdisengaged.

In one embodiment, valves 706 and 708 are used to control the flow ofgeothermal heated fluid from the geothermal water source 702. When powergeneration is initiated, valve 706 is open and valve 708 is closed.Geothermal heated fluid flowing through conduit 710 flows into conduit712 and is channeled into separator 714, where the fluid is separatedinto steam and water. The water flows through conduit 716 to bedelivered to the shellside inlet of heat exchanger 704. The steam flowsto turbine 718, which drives generator 720. When power generation isdisengaged, valve 706 is closed and valve 708 is open. The geothermalheated fluid bypasses the power generation system and flows directly toheat exchanger 704.

Referring to FIGS. 8 a and 8 b, side and front elevations of anillustrative agricultural trellis are shown, respectively. The trellismay be used to train and support an agricultural plant, such as agrapevine. The trellis comprises a post 802 and may comprise one or morecross-arms 804-808. The post and cross arms are generally comprised ofwood. The cross arms may be coupled to the post with attachment meanssuch as nails or screws. The cross arms may have openings as shown at810. The post may also have openings as shown at 812. The openings inthe post and in the cross arms may be, for example, a hole drilledthrough the cross arm or the pole. The openings may receive wires asshown at 852-860 in FIG. 8 b. The cross arms 804, 806 and 808 receivecatch wires 854, 856 and 858, respectively. Each of the cross arms shownin FIG. 8 a is shown with two openings to receive two catch wires. Theopening 812 receives fruiting wire 860. An additional opening 812 in thetrellis post may receive a net wire. The fruiting wire 860 is used totrain the growth of the plant. For example, the fruiting cane of agrapevine may be trained onto the fruiting wire. One or more catch wires854-858 may be used for additional support of the foliage and fruit ofthe grapevine. A net wire 852 supports a protective net as shown inFIGS. 9 a-9 b.

Referring to FIGS. 9 a-9 b, an illustrative trellis with integrated dripand spray irrigation systems and protective net is shown. FIG. 9 a showsthe trellis with the protective net retracted. In FIG. 9 b, theprotective net is deployed. Trellis 900 comprises post 902. A dripirrigation line 904 is coupled to post 902 near the base of the post.The drip irrigation line provides irrigation water to the groundsurrounding the trellis. In some embodiments, a spray irrigation line906 is coupled to post 902. The drip irrigation line and the sprayirrigation line are coupled to an irrigation channel of the irrigationmanifold 230. Irrigation water is channeled to the top of trellis 900 bytubing 908 coupled to the spray irrigation line 906. A nozzle 910 iscoupled to the terminus of the tubing. The nozzle delivers a spray 912of heated irrigation water to the area surrounding the trellis. In thismanner, plants may be protected from damage due to cold weather damage.A protective net 914 is supported by net wire 852. The protective netprovides protection to the plant from the effects of cold weather. Theprotective net may comprise, for example, a fabric or plastic mesh. Theprotective net is unfurled to partially or fully cover the plant asshown at 914 in FIG. 9 b. When not in use, the protective net may berolled or otherwise formed into a more compact shape as shown at 914 inFIG. 9 a. The protective net may be secured in a rolled form by afastener, for example, a strap with a hook and loop fastener.

Referring to FIGS. 10 a-10 b, illustrative first and second spraypatterns of a nozzle in a spray irrigation system are shown. A firstspray pattern, shown in FIG. 10 a, is oriented substantially alongfruiting wire 1002. Heated irrigation water issues as a spray 1004 fromnozzle 1006. The nozzle 1006 is affixed to trellis post 1008. Additionaltrellis posts are shown at 1010 and 1012. In the trellis system shown, aspray irrigation system is affixed to alternate trellis posts such thatonly one of every two trellis posts has a spray nozzle. In someembodiments, a nozzle is affixed to each trellis in a trellis system. Itwill be recognized that other distributions of spray irrigation systemsamong trellises in a trellis system are possible.

A plant trained along the fruiting wire will receive substantialcoverage from a spray oriented as shown in FIG. 10 a. In trelliseshaving two fruiting wires 1052 and 1054, as shown in FIG. 10 b, a spraypattern 1056 oriented to provide coverage to both fruiting wires may bedesirable. The spray pattern shown in 10 b may also be desirable toprovide coverage to trellises having foliage and fruit supported bycatch wires (e.g. 854) mounted via openings at the ends of a cross arm(e.g. 804).

Referring to FIG. 11, illustrative flow chart 1100 for the operation ofthe drip and spray irrigation systems is shown. The method begins atdecision diamond 1102, in which the control system compares the airtemperature as measured by an air temperature sensor against a firstthreshold temperature. If the air temperature is lower than the firstthreshold temperature, the method proceeds to decision diamond 1104, inwhich the control system determines whether the air temperature has beendeclining over a predetermined period of time. If the air temperaturehas been declining, the method proceeds to block 1106. At block 1106,heated water is routed to the drip irrigation system. The methodproceeds to block 1108, at which the spray heating system is initiated.At decision diamond 1110, the control system compares the airtemperature against a second threshold temperature. If the airtemperature is greater than the second threshold temperature, the methodproceeds to decision diamond 1112 where the control system determineswhether the air temperature has been rising over a predetermined periodof time. If the air temperature has been rising, the method proceeds toblock 1114. In block 1114, the flow of heated water to the dripirrigation system is halted, and unheated (ambient temperature)irrigation water is routed to the drip irrigation system. The methodthen proceeds to block 116, at which the flow of irrigation water to thespray irrigation system is terminated.

In some embodiments, additional sensor inputs or logic will be used todetermine whether steps 1106 or 1108 or both will occur when theconditions presented in decision diamonds 1102 and 1104 occur.Similarly, additional sensor inputs or logic may be used to determinewhether steps 1114 or 1116 or both will occur when the conditionspresented in decision diamonds 1110 and 1112 occur. For example, duringsome weather conditions, drip irrigation with heated water will bedesirable but spray irrigation with heated water is unnecessary.

Referring to FIG. 12 a, illustrative state diagram 1200 for theoperation of the drip irrigation system is shown. The controller of thecontrol system may be configured to enable the drip irrigation system toprovide no irrigation water, unheated irrigation water, and heatedirrigation water. At state 1202, no irrigation water is provided by thedrip irrigation system. At state 1204, unheated irrigation water isprovided by the drip irrigation system. At state 1206, heated irrigationwater is provided by the drip irrigation system. The controller mayenable transitions between any of states 1202, 1204, and 1206 as shownin state diagram 1200.

In an illustrative embodiment, the drip irrigation system may have aninitial state 1202 of no irrigation water being provided. If irrigationis required, the controller may transition the drip irrigation systemfrom state 1202 to 1204, to provide unheated irrigation water to thedrip irrigation system. If the air temperature falls below a firstthreshold and the air temperature is declining, the controller maytransition the drip irrigation system from state 1204 to state 1206, toprovide heated irrigation water to the drip irrigation system. Thecontroller is configured to open a valve 414 disposed between thegeothermal heated water source and the heat exchanger to enable atransition between these states. If the air temperature subsequentlyrises above a second threshold condition and the air temperature isrising, the controller may transition the drip irrigation system fromstate 1206 to state 1204, closing valve 414. In some cases, the airtemperature may be below a first threshold temperature and decliningwhen the irrigation system is first initiated. In this case, thecontroller may transition the drip irrigation system from state 1202 tostate 1206.

Referring to FIG. 12 b, illustrative state diagram 1250 for theoperation of the spray irrigation system is shown. The controller of thecontrol system may be configured to enable the spray irrigation systemto provide no irrigation water and heated irrigation water. At state1252, no irrigation water is provided by the spray irrigation system. Atstate 1254, heated irrigation water is provided by the drip irrigationsystem. The controller may enable transitions between states 1252 and1254, as shown in state diagram 1250.

In an illustrative embodiment, the spray irrigation system may have aninitial state 1252 of no irrigation water being provided. If the airtemperature falls below a first threshold and the air temperature isdeclining, the controller may transition the drip irrigation system fromstate 1252 to state 1254, to provide heated irrigation water to the dripirrigation system. The controller is configured to open a valve 414disposed between the geothermal heated water source and the heatexchanger to enable a transition between these states. If the airtemperature subsequently rises above a second threshold condition andthe air temperature is rising, the controller may transition the dripirrigation system from state 1254 to state 1252, closing valve 414.

Typically, when heated irrigation water is provided to the dripirrigation system, heated irrigation water will also be provided to thespray irrigation system. However, in some embodiments, the controlsystem is configured such that the spray irrigation system may provideheated irrigation water while the drip irrigation system providesunheated irrigation water.

A system for providing drip and spray irrigation with heated water hasbeen described. Drip and spray irrigation systems may be mounted toagricultural trellises to provide heated irrigation water at groundlevel and as a spray at an elevated level relative to the plantsupported by the trellis.

It is to be understood that the detailed description of illustrativeembodiments are provided for illustrative purposes. The scope of theclaims is not limited to these specific embodiments or examples.Therefore, various process limitations, elements, details, and uses candiffer from those just described, or be expanded on or implemented usingtechnologies not yet commercially viable, and yet still be within theinventive concepts of the present disclosure. The scope of the inventionis determined by the following claims and their legal equivalents.

1. A control system for an irrigation water heating system, the controlsystem comprising: a controller; memory operatively coupled to thecontroller; a first threshold value stored in memory a sensoroperatively coupled to the controller; a geothermal heated water source;a heat exchanger; a valve disposed between the geothermal heated watersource and the heat exchanger; and the controller configured to performa periodic comparison between the sensor input and the first thresholdvalue, and if the sensor input value falls below the first thresholdvalue, the controller generates an instruction to open the valve.
 2. Thecontrol system of claim 1, wherein the sensor is an air temperaturesensor.
 3. The control system of claim 1, further comprising a secondthreshold value stored in memory, wherein the controller performs aperiodic comparison between the sensor input and the second thresholdvalue stored in memory, and if the input value rises above the secondvalue stored in memory, then the controller generates an instruction toclose the valve.
 4. The control system of claim 1, further comprising anirrigation manifold, the irrigation manifold comprising: a first valveto regulate a flow of water into a first channel; and a second valve toregulate a flow of water into a second channel, wherein the controllergenerates an instruction to open the first valve and the controllersubsequently generates an instruction to close the first valve and openthe second valve.
 5. The control system of claim 1, further comprising aspray heating system manifold, the spray heating system manifoldcomprising: a first valve to regulate a flow of water into a firstchannel; a second valve to regulate a flow of water into a secondchannel; wherein the controller generates an instruction to open thefirst valve and the controller subsequently generates an instruction toclose a first valve and open the second valve.
 6. A control system foran irrigation water heating system, the control system comprising: acontroller; memory operatively coupled to the controller; a firstthreshold value stored in memory an air temperature sensor operativelycoupled to the controller; a buffer in memory configured to store datagenerated by the sensor a geothermal heated water source; a heatexchanger; a valve disposed between the geothermal heated water sourceand the heat exchanger; the controller configured to periodicallyanalyze the air temperature sensor input and the first threshold value,wherein if the input falls below the first threshold value and if theair temperature is decreasing, the controller generates an instructionto open the valve.
 7. The control system of claim 6, further comprisinga second threshold value stored in memory, wherein after the controllerhas generated an instruction to open the valve, the controller performsa periodic comparison between the sensor input and the second thresholdvalue stored in memory, wherein if the input rises above the secondthreshold value and if the temperature is rising, the controllergenerates an instruction to close the valve.
 8. The control system ofclaim 6, further comprising an irrigation manifold, the irrigationmanifold comprising: a first valve to regulate a flow of water into afirst channel; a second valve to regulate a flow of water into a secondchannel; the controller configured to generate an instruction to openthe first valve and the controller subsequently generates an instructionto close the first valve and open the second valve.
 9. The controlsystem of claim 6, further comprising a spray heating system manifold,the spray heating system manifold comprising: a first valve to regulatea flow of water into a first channel; a second valve to regulate a flowof water into a second channel; wherein the controller generates aninstruction to open the first valve and the controller subsequentlygenerates an instruction to close a first valve and open the secondvalve.
 10. A control system for an irrigation water heating system, thecontrol system comprising: a sensor; a geothermal heated water source; aheat exchanger; a means for regulating a flow of water between thegeothermal heated water source and the heat exchanger; and a means forcomparing the sensor input to a first threshold value, wherein if asensor input value falls below the first threshold value, water isconducted from the geothermal heated water source to the heat exchanger.11. The control system of claim 10, wherein the sensor is an airtemperature sensor.
 12. The control system of claim 10, furthercomprising a means for comparing the sensor input to a second thresholdvalue, wherein after water is conducted from the geothermal heated watersource to the heat exchanger and if a sensor input value rises above asecond threshold value, the flow of water between the geothermal heatedwater source and the heat exchanger is stopped.
 13. The control systemof claim 10, further comprising an irrigation manifold, the irrigationmanifold comprising: a first means to regulate a flow of water into afirst channel; and a second means to regulate a flow of water into asecond channel, wherein a flow of water is conducted into a firstchannel and the flow of water into the first channel is subsequentlystopped, and a flow of water is conducted into a second channel.
 14. Acontrol system for an irrigation water heating system, the controlsystem comprising: an air temperature sensor; a geothermal heated watersource; a heat exchanger; a means for regulating a flow of water betweenthe geothermal heated water source and the heat exchanger; a means forcomparing the sensor input to a first threshold value; and a means fordetermining whether the air temperature as measured by the airtemperature sensor has been decreasing, wherein if the air temperaturefalls below the first threshold value and the air temperature has beendecreasing, the water is conducted from the geothermal heated watersource to the heat exchanger.
 15. The control system of claim 14,further comprising: a means for comparing the sensor input to a secondthreshold value; and a means for determining whether the air temperatureas measured by the air temperature sensor has been increasing, whereinafter water has been conducted from the geothermal heated water sourceto the heat exchanger, if the air temperature rises above the secondthreshold value and the air temperature has been increasing, the flow ofwater between the geothermal heated water source and the heat exchangeris stopped.
 16. A controller for an irrigation water heating system, thecontroller transitioning the system state for a drip irrigation systembetween the following states: a first state in which the drip irrigationsystem is off, a second state in which the drip irrigation systemprovides unheated irrigation water, a third state in which the dripirrigation system provides heated irrigation water; and the controlleropens a valve disposed between the geothermal heated water source andthe heat exchanger to enable the transition from the second state to thethird state; the controller closes the valve to enable the transitionfrom the third state to the second state.
 17. A controller for anirrigation water heating system, the controller transitioning the systemstate for a spray irrigation system between the following states: afirst state in which the spray irrigation system is off, a second statein which the spray irrigation system provides heated irrigation water;and the controller opens a valve disposed between the geothermal heatedwater source and the heat exchanger to enable the transition from thefirst state to the second state; the controller closes the valve toenable the transition from the second state to the first state.
 18. Amethod for controlling an irrigation water heating system, the methodcomprising using a controller to perform a periodic comparison between asensor input value and a first threshold value stored in memory, and ifthe sensor input value falls below the first threshold value, generatingan instruction with the controller to open a valve between a geothermalheated water source and a heat exchanger.
 19. The method of claim 18,further comprising: after the valve has been opened, using a controllerto perform a periodic comparison between a sensor input value and asecond threshold value stored in memory; if the sensor input value risesabove the second threshold value, generating an instruction with thecontroller to close the valve.
 20. The method of claim 19, furthercomprising: generating an instruction with the controller to close asurface water valve between a surface water source and an irrigationmanifold, if the sensor input value falls below the first thresholdvalue; and generating an instruction with the controller to open thesurface water valve, if the sensor input value rises above the secondthreshold value.
 21. The method of claim 19, further comprising openinga valve disposed between the geothermal heated water source and aseparator in response to a sensor input.
 22. A method for controlling anirrigation water heating system, the method comprising: using acontroller to perform a periodic comparison between a air temperaturesensor input value and a first threshold value stored in memory; if theair temperature sensor input value falls below the first thresholdvalue, using the controller to determine whether the air temperature asmeasured by the air temperature sensor is decreasing, if the airtemperature is decreasing, generating an instruction with the controllerto open a valve between a geothermal heated water source and a heatexchanger.
 23. The method of claim 22, further comprising: after thevalve has been opened, using a controller to perform a periodiccomparison between the air temperature sensor input value and a secondthreshold value stored in memory; if the air temperature sensor inputvalue rises above the second threshold value, using the controller todetermine whether the air temperature as measured by the air temperaturesensor is rising, if the air temperature is rising, generating aninstruction with the controller to close the valve.
 24. The method ofclaim 23, further comprising, if the air temperature sensor input valuefalls below the first threshold value and the air temperature isfalling, generating an instruction with the controller to close asurface water valve between a surface water source and an irrigationmanifold; and if the air temperature sensor input value rises above thesecond threshold value and the air temperature is rising, generating aninstruction with the controller to open the surface water valve.